Continuous inductive train control system



Sept. 22, 1931.` w. D. HAILES CONTNUOUS INDUCTIVE TRAIN CONTROL SYSTEM Filed Oct. 3G, 1925 2 Sheets-Sheet l 0 .Tw m im@ m6 Tu o@ Pm sept. 22, 1931. w. D. HAILES Y 1,824,749

CONTINUOUS INDUCTIVE TRAIN'CONTROL SYSTEM Filed Oct. 50" 1925 2 Sheets-Sheet 2 l (Y) (E. sa Q N lL- sa P x....m N Q Q* h,- U :if

Lo n 0') ,lwzo. 12 3Q 0') (D CD @www BYgg/vl Patented Sept. 22, 1931 wIELIAM.D.,HAILEs, OE EooHEsTE'E, NEw YoRKAssIGNoE'To ENEEAL 'EAILWAE `v sreNA'L ooMrANY, or EooHEsTEE, NEW. vom:y

.'coNTTNUoUsrNDUCTIvE TEAIN CONTROL SYSTEM v "Application md october 3o, 1925. serialNe A65,816.

` This invention relates. to automatic train controlsystems of the continuous inductive type, and more particularly concerns a method of Vconditioning the carfcarriedy ap- 5 paratus of such a lsystem for. train operation over a section of trackway which'is not` equipped for .train control.

The .present applicationis continuation in part of applicants co-pendingapplication Ser. No. 717 ,767 filed June 4, 1924:.,A

In applying a system` of automatictrain controlzto a railwaysystem, itis necessary to provide for the operation of trains equipped for train control` overisectionsof trackway not equipped for: train. control operation.

In the' continuous inductive type of .train control' system, in which currents. flowin the track rails lcontinuously under favorable traffic conditions andare cut o under'un-jA favorable traffic conditions,y and in which influences corresponding .to 'these v currents are vinductively A received- Vby vthe moving vehicle,' a method-has been: devised forplacing the car-carried .control ap-paratusin its non-control condition asthe train entersunequipped sections of .'trackway'.l iwhich. is commonly known as the.excessenergyloop method. In this scheme, vanexcess'amount of .current is `supplied from the trackway for short distances of fvehicle travel at points where the vehicle lisiabout .to enter unequipped territory, and means areiprovided' on the locomotive for'. placing the automatic equipment @in its yinactive Icondition 3 given amount .of Eenergy with .its sensitivity substantially reduced or Vdiminished bysome suitable manually actuable means under the control of the engineer, *the'amount of en# erg'y supplied by the excess energytrack way loop being the only-amount suppliedto at one endof each of'thexusual trackblocks.

.On certain railwaysystems however, vand particularly on l railwayselnploying, .electri .frequenciesI for. ltrain control purposes, so

only if the receivingiequipment receives' av cal current for propulsionpurposes andusing the track `rails as a return, vit is necessary or advisablev to vuse currentsof-frequencieshigher than the usual commercial 55 that the `propulsion current fcanbeniore readily filtered outaby the car-carried receiving apparatus ofthe train 'control equipment. lVhen currents of, comparatively high frequency are impressedupon the track rails 6o v at one end of a block, the current .flowing in the track rails of the block will vary :greatly at Ydifferent points in the block due to the .reactance of the trackrails, kthe leakage `between' the rails andfor variousotherreasons. This variation incontrol current-iin. thetrack rails of` a single block is very great, sometimes ruiming as high'astwentytimes as much current flowing inthe rails at^ the point where the energy. is impressedIas is flowing in the rails at the opposite endtof theblock. u Y ."[t isapparent that when the eXcessenergy method of conditioning the car-carried rtrain control equipment for'. operation ,in un#A 75 equipped territory is `el'nployedfon railways using high frequency train controlV currents, the car-carried receiving and controlequipf mentmust perform its `rvarious functionsfof control and yof beingrendered inactive forvtravel-over unequipped sections 'of trackway mum amount o yenergy available. a-longuthe trackway is; represented by units,` that 20 vS5 units are supplied tothe track rails at one end of eachzblock,v and that 30 unitsare supplied' to the excess energy loop or section at the entrance `to unequipped territory, then'the car-carried receivingand controlY equipment must respond properly touenergy 'varying from; one unit, at one end Vof.eachblo'ckl to V20 units atv theaother,` and` `whei'rthe sensi# tivity ofv ,thereceivers lis. reducedv to:v render the apparatus inactive,'the1 apparatus-must $5 not respond to 2O units butmustgrespond to ,30, unitsto be set-in the inactivestate. In actual' practice, the @energy supplyin at-he variousblocksand at the -various excess en -V ergyV points varies-,toa certainextent-sothat i190 the theoretical problem set forth above is magnified, and the limits within which the control apparatus must operate distinctively are very narrow.

With 'the above and other considerations for causing its distinctive operation inre-V spoiise to variations in sensitivity and to comparatively small differences in energy supply. Morespeciiically,it is proposed to provide a system of thc'type described in which a transformer iseinployed in a tuned vehicle receiving circuitA and in which the voltage transformation .ratio of the trans-` former and the 4tuning of the receiving apparatus is changed to diminish the sensitivity of the receiving equipment to a definitely fixed degree when the vehicleV is passing over an excess energy section preparatory to entering unequipped territory. Y

It is'furtlier proposed to provide a system i of the type described employing, a suitable car-cairied relay for responding to the control circuits in the track rails in which the proper operation yof 'such relay is checked at every point where the vehicle enters unequipped territory, the :complete operation of. such relay at these points being necessaryy to render'the car carried control equipment inactive.`

Other objects, advantages and characteristic features of the invention will be pointed out and will become apparent as the description thereof progresses. f i Y In describing the invention 'in' detail, reference will be made lto the accompanying drawings in which lxFig:'lvrepresents in a diagrammatic and conventional manner, the car-carried apparatus for a traincontrol system embodying the present invention, together with a typ-- icalwarrangement "of trackway'dev-ices and circuits for use therewith;4 A i,

F ig. 2 shows a modified method of reduc! ing the sensitivity of the receiving and amplifying apparatus of atrain control Vsys-V tem, and Y t Figs andv4 show further modifications of asmeansfor reducing the sensitivity .of-

the car-carried receiving equipment. s s Referring more particularly to Fig. l, th usualwayside` apparatus for an automatic Ytrain control system of the'continuous inducli tive type has been shown, together with an y excess energy section and a portion vof track-V way which is unequipped for .automatic train control. f Thistrackwayequipment1 is well known 'to *thosel skilled,l in the ,art and 675 has-been described in detail in the application of Charles S. Bushnell, Ser. No. 723,048, filed June 28, 1924 and for this reason only a very brief description of this equipment will be given. The track rails l are shown divided into blocks by the usual insulating joints 2, the block I, the adjacent end of the block H, and excess energy section J, and a portion of a block K in non-train controlterritory havingv been shown. As certain ofthe vdevices used in theseveral blocks are 'substantially identical, like reference characters having distinctive exponents have been yused to designate the corresponding elements inthese. blocks.

The usual track batteries 3 are connected across the track rails 1 at the exit Vends of the blocks as shown, and energize the Well known track relays T, connected across the track rails at the entrance ends of the blocks.

The usual alternating train control current `transformers 4 connected in series with the track battery 3 as shown.i The transformers 4 are energized through the front contacts 5 and 6 of the track relays T from a second transformer. 7 l connected across a transmission line 8. It is evident that this train controlY current, usually Aterniedr the track phase current, will be. supplied to the two track rails ofa block in series so long as the track relay at the entrance endof the` next block in advance remains energized, or. in other words, so long as no train is located insuch advanceblock.. n

The rails'of the excess energy section J areconstantly supplied with alternating current from the transformei' 9, this transformer supplyinga larger amount of current to the rails of this section than is sup- A plied by thetransformerf?. It should beunderstood thatwave wires ofthe Well known type,flying parallel to the track rails and inclose proximity thereto, might beemployed toy carry this excess current in place of the track rails if desired, the resultant magnetic field for transmitting influences to the'vehicle carried receivingapparatus being obviously 'the same in either case. An alternating current track relay ,10 is connected across the trackrails at the entrance end of the excess energy section J, and` acts with the track relay T at the entrance end of the first block IK ofl theunequipped or non-train control territory, to control the energization of a linen relay 11 through a cir cuit which is obvious from the drawings. The line relay 11 controls the energization of the transfor1ner4 supplying track phase train'control current to the track rails of the block I The purpose of this arrangementis to provide adequate automatic train control up to the point at which unequipped or non-control territory is entered If, for instance',- a train'werielocated near lthe enterritory, the proper automatic control `shouldbe imposed to bring the train` in block I to a stop before it could enter the block K. This'ariangement of controlling the train control current in the last blockr of the equipped trackway in accordance with traffic conditions in the first block of unequipped trackwayfmay be dispensed with if desired, but it is thought preferable to employ this additional protective control for the reason that the engineer, while traveling in equipped territory, islinclined to expect full protection through the automatic equipment. Obviously ifrthe last block of equipped trackway were not controlled `in accordance with traiiic conditions inthe iirst unequipped block, the automatic control apparatus might under certain conditions indicate clear traffic conditions aheadwhen such conditions Vdo not in fact exist.

Wayside signals of-the semaphore, color light, or other suitable typ-e may or may not be used in connection with the trackway equipment. In the drawings, semaphore wayside signals Z of the usual type have` been illustrated in a conventional manner A only, a showing of their operating devices and connectionspbeing omitted as these devices form no part of the present invention and are well understood byy those skilled in the art.

As the method of renderingA the car-car- 'ried apparatus inactive for 'travelf'over trackway which isunequipped fortrain c ontrol, which comprises the present invention, is particularly applicable to'railwaysvemploying electrical current for' vpropulsion purposes and returning this current'through' the track rails, the trackway equipment has been shown arranged for electrical'propulsion. Impedance bonds 12 of the well known type are connected across the track rails at each end side of theinsulating rail joints 2,

and these impedance bonds arel connected to-` gether at their `midpoints 'to conduct the propulsion current Vpast these lJoints. VAn alternating current generator AGr has been shownk connected vbetween the track-rails 1V and a trolley wire 13, the connection between the generator and thetrack rails being through' a balanced' impedance' coil'14. It should be understood that this showingr of the electrical propulsion equipment is illustrative only, and that a third rail or othersuitable system of propulsion current supply might be used without departingfrom the spirit'of the invention. l. v

Referring now morelparticularly'to the car-carried equipment, a railway vehicle has been conventionally illustrated in the block H by the wheels and aXles-15,the normal directionKY of vehicle I, travel being. indicated by the arrow. Avprop'ulsion motor 116, conmay or may not be provided with laminated iron cores, are carried in front of the leading axles of the vehicle, and in inductive relationto vthe track rails 1.V These receiving coils'are .connected in such a manner that fthe voltages induced therein by currents flowing in opposite directions in the two'track rails are cumulative. The receiv-v ing coils 18 and 19 are connected to an audion tube amplifier lof the type now` common in train control practice, through; a filter circuit; This filter circuit is of the type shown and described yn my co-pendingapplication Ser. No. 717,767, filed June 24, 192et-of which the present application is acontinuation in part, and consists of an input circuit comprising a condenser 2O and a reactance coil 21, preferably iron cored, connected in-series with the primary windingv of an auto transformer 22. f The secondary winding of the auto transformer 22 is connected acrossl a variable condenser 23 and'to the input circuit of the amp'liiier through` the back contact 24 and contact finger 25 of the push button relay 26.V

'The amplifier is of a type well known to those familiar with train control practice, and as its particular construction forms no part of the present invention and has rbeen describedin detail in my co-pending application, identied'above, a detailed description thereof willV not be given. The usual. three-element audion tubes 27 are used in the amplifier, and reactance coupling ofthe well knowntype has been provided between them, theiron cored reactance coil 28 being employed, VThe filaments 29 of the tubes 27 are connected in series andthe current through them is limited by the resistances 30 and the ballast lamp 32. The plate and filament circuits are energized by the-batteries 33 and 34 respectively-in the usual manner4 as clearlyzshown. v i i The push button relay 26 is used merely for repeating the" operation vofa push butpoint in the locomotivel cab, the relay 26 Vnected between the vehicle axles and a trol-1 v being .usually carried in a suitable lrelay housing on thetender or other suitable point together `with theother relays and devices of .the kkcar-carried control equipment.

`The kcar-carried apparatus includes a main relay MR, a secondary relay S and a non-i control relay N C. These relays are preferably'of the direct current type and are suitl ably constructed and balanced to withstand thevibration and shock kof railway usage.

The secondary relay Vandthe non-control relay NC are madeHslowxacting-by somesuitable means, ,for drop-away, the purpose p ofr 'this' `slow acting o feature being `brought' out in connection with the description of th operation of the system.

The vehicle brakes may be controlled in any suitable manner and by means of any one of a number of well known devices used for this purpose. As the initiation of an automatic brake application is usually effected by the de-energization of some suitable electro-pneumatic valve, cam starting, magnet or other electro-magnetic device, a normally energized brake applying device has been conventionally illustrated at BA, it being assumed that this device will act in some suitable manner to initiate a restrictive brake application when de-energized.

Operation Fe'g. 1

The Ycircuits and devices have been shown in their normal operating positions in the drawings,'that is, their positions are such as would be assumed with a train running under clear traffic conditions over a section of trackway which is equipped for automatic train control. Y

' lVith clear traffic conditions existing, that is, with no train, broken rail or other hazard in the block in which the train under con- Y sideration is located or in the next block in advancev thereof, alternating train control current will fiow in the two track rails of each equipped block in series, this current being supplied from the transmission line 8 through the transformers 4 and 7 and the contact fingers' 5 and 6 of the track relay T, the circuit being obvious from the drawings. This current will induce a voltage in the receiving coils 18 and 19 which will be impressed upon the filter circuit of the carcarried equipment. The input and output circuits ofthe filter are tuned to the frequency of the train control current, and the voltages induced by the propulsion current which is of a distinctive frequency, flowing in the .track rails will therefore be sup-` pressed and voltage of train control frequency only will be impressed on the input circuit of the amplifier. It is sometimes found desirable to improve the tuning of the filter circuit by varying the point at which the primary circuit is connected to the transformer winding. In this connection it shouldbe noted that if the propulsion current is equally balanced in the two track' rails, no voltage of propulsion fre quency will be induced in the receiving coils, asY these coils are so connectedthat currents flowing in the same direction in track rails will induce voltages which are in opposition in the twocoils. Unbalancing of the propulsion Vcurrent in the track rails frequently occurs, however, and for this reason the filter circuit is usedV tov Ykeep voltages of propul sion frequency out of .the amplifier. p

The voltages delivered to the amplifier are aniplied and impressed on the windings of the main relay MR through a circuit which may be traced as follows z-from the plate 36 of the last tube 27 of the amplifier, through wires 37 and 38, the winding of the main relay MR, wires 39 and 40, contact finger 4l and back contact of the push button relay 26, and wires 42 and 43 to the filament circuit of the last tube 27 of the amplifier. With the main relay MR thus energized, its contact fingers 44, 45 and 46 l,

are attracted and a circuit for energizing the brake applying device BA is completed, which circuit is obvious from the drawings. Vith the brake applying device BA energized, the train may proceed without restriction in the clear block. The energization of the main relay MR also causes the energization of the secondary relay S through a circuit which may be traced as follows :-from the battery terminal B, contact finger 47 and back contact of the push button relay 26, wire 48, contact finger 45 and front contact of the main relay MB, wire 49 and Winding of the secondary relay S to the battery terminal C. lVith the secondary relay S energized, its contact fingers 50, 51 and 52 will be attracted.

Vhen the vehicleunder consideration enters a caution or danger block, that is, a block in which aV train or other hazard is located or the first block to the rear thereof, no train control current will flow inl the track rails, the receiving coils 18 and 19 will not haveV voltages of train control free quency induced therein, the amplifier input circuit willnot be energized and the main relay MR will consequently be cle-energized, retracting Yits contact fingers 44, 45 and 46. The retraction of the contact fingers 44 of the main'relay-MR causes the de-energization of the brake applying device BA and a restrictive brake application results. This brake application is of a nature depending on the particular brake control apparatus used, and may be a single, fullservice application, a speed distance restriction or any other suitable and well'known automatic restriction may be imposed.

Consideringnow more particularlythe operation of the non-control apparatus coinprising the present invention, assumer that the train under consideration is proceeding in the block I under clear traffic conditions, this being the last block in a section of track- Way-wliich is equipped for automatic train control, and that the engineer wishes to condition ythe car-carried apparatus'for travel over an unequipped section of trackway, the first block of which is 1 represented by the block K in the drawings. As the train enters thev excess energy section J, the engineer depresses the push buttonl to so retain it throughout such section,thus energizing the push button relay 26 through a circuit which is obvious; VThe energizationofthe pushbutton vrelay'26 causes its contact finger 25 to beattracted, breaking the baci; icontact 24 and engaging thefront contact 53. It is evident from thedrawings that the closing of 4:and front contact Aof the main relay MR, wire ',.con'tact linger land back contact fof the secondary relay S, wires 61 kand 62 and l.the winding of the non-control relay N C yto the front contact 53 of the push button relay 26 changes the connections to the inputocir-v cuit ofthe amplifier. This change in the input circuit connections reduces'the sensitivity of the receiving system for two reasons; first because it changes thel input circuit of the amplifier to cause it toy be connected across` the .primary` winding of the :auto transformer 22, instead of across .the secondary as before, therebyreducing'the voltage applied to the inputcircuitfby .the` ratio'of transformationof the auto transformer and second, by reason of the fact that the autotransformer is partially detuned because of the transfer of'thecondenser 54from being connected across the secondary to being connected across the primary. winding thereof.

The values of the capacityof the condensers` 23 `and 54 are so chosenas to give the desired degree of detuning and also are chosen to resonate with the` transformer at lthefre- -v quency used when these two condensersare comiectedin parallel across the secondary V,winding of the transformen Although the sensitivity of the receiving equipment hasbeen substantially reduced by the change of transformation Aratio andthe Yde-tuning described above, the energy flowf ing in the track rails of the excess energy secltionJ isstill sufficient to induce such a volt.- age inthe receiving coils 18 and.19 that the amplifier is maintained energizedand its output circuit delivers anormal current. The main relayMR however,is momentarily deenergized for the reason that the circuit connecting this relaywith the amplifieroutput circuit is broken bythe attraction of the contact finger 4l ofthe push button relay 26.r

VThe de-energization of the vmain yrelay' MR retracts the contact finger 45, thereby breaking at a second place theenergizing lcircuit for the secondary relay S, (whichwas initially kbroken at contact finger. 47 of relay 26, upon closure of `35)' yvhic'h circuit has beentraced above. The de-energization of the secondary relay S causes the retraction of its contact finger'O, and when this contact nger engages its 'back contact, an alternative energizing circuitfor the main relay MR is completed, whichcircuit may be traced as follows fromthe plate 36 of the lasttube 2,7y of the amplifier, through wires V37 and 33, the winding ofthe main relay MR,.wires 39 and 56 back contact and contact finger 50 ofthe secondaryl relayrS,and

wires' and 43 to the filament circuit of theV amplifier. As soon asvthe` main relay MR is energized, the push lbutton'relay 26 being still in its energized condition, and secondary relay S being de-energized, acircuit is completed.. for e1,lengizing` the nonecontrol `relay. N C, which circuit may be traced as follows :-from the battery terminal B, contact finger 58 and `front contact of the push button` relay 26, wire 59, contact finger 46 the battery terminal C. Once energized'the non-control relay .C is maintained energized.;

y'64 and front contact of thenon-control relay N C,`wires and 62, and thewindingof the non-.controlrelayyNC to the battery terminal G. Assoon Aas the non-control relay NC is energized, an` energizing circuit for the brake applying'` device BA is completed throughthe contact finger 66 and front con- .tact ofthis non-control relay, this energizing circuitl being. obvious from the drawings; lWith .the brake applying device BA ene-rgized, the ltrain under consideration may 1;.

proceed through the unequipped section of traf'clrwayv without restriction, the de-energizationofthe mainfrelay MR due to the lack of train control current inthe traclr'rails of unequipped trackway having no effect.- upon. the energization of the .non-control relay NG, as this relay'is maintained-.energized through a "stick circuit including its own front contact ,and a-.back'contact of the secondary relay S.

. The relayS, as mentioned above,.is designedv to be slow to release, butonlyvery slightlyfslower to releasethan isvrelay MR.

Thus, when 26 picks up, relays MRV and S are simultaneously yrie-energized at fingersfll enough to release` to insure that `MR lreleases 'before S, or, that contactv` finger 44 `breaks ContactV before contact finger 50 .makesy contact. This, of course,results in a momen- .taryy de-energization offBA,-followed kby a rer-energization, and sinceatl least several Vsecondsv is required, in, an air brake system, after initiationthereof, forthe actual application of thefbrakes to occur, yno brakeapplication here takes place. At the same v Also, as above mentioned, relay NC is slow to release, wherebyto insurethat lBA benot degenergized due to "momentary interfering currents of proper frequency during travel tliroughjnon-.train ,control territory. Asisume, for instance, that while traveling `through non-train control territory momentaryv interfering current, is encountered such as.vv to result in pick-up of relayMR. This will cause relay Sto pick up tot-hns .break retractionof the fingers of relay 1,95 and 47 respectively, andS -is just slow i i i 'thestick circuit of relay NC at contact finger 52. vIf relay NC 'Were quick to release, it would drop and initiate BA. And subsequent drop away of MR and in turn of S vvould'not complete the pick-up circuit for NC, so that NC'ivo'uld remain de-energized However, With NC slow to release, as shown andV described, it holds up long ,enough for MR to drop again, to in turn drop Sto thus; re-energize-NC. Thus such momentary interfering current has no effect on BA.V l f Y 'f Fromfthe above description of the operation ofthe car-carried' apparatus'` upon the entrance of atrain to non-control territory, Vit Will be observed that itis necessary lfor the main relay to 'be completely picked up from its full de-energized position While the "sensitivity of the re'ceivingequipnient is reduced and the train is travelingover the excess energy section.' In` the Asystems previously proposed for rendering thecar-carried apparatus inactive by means of an excess energy loop or section, it Was merelyne'ces- -sary thatA the main relay or equivalent device be maintained' in its energized position Vvvher'i the'a'mpliiier sensitivity Was reduced la`I1d.the1eXcess`*energy section traversed. It

'is clear that the arrangement of the present invention-'insures that the main relay MR 'is lin proper ,operating condition when the change. from lequipped to unequipped track- Way is made. For` example "if the contact fingers of the Vmain relayl were jammed or stuck in their attracted position it-Would vbe possible to temporarily energize the noncontrol relay NC, since the secondary relay S is di-energized due to contact finger 47 of relay 26 being attracted. Thus relay `NC Would'fbe energized and Ythus remove BA from under control of the main relay MR and itself assume control of YBA. Immediately however, upon the car entering the 'non-train control territory, upon manually operable contact being released, relay S would be energizechit being borne in mind that contact finger of relay MR is assumed to lbe stuck or jammed in attracted position. This energization of secondary relay S would` break the stick up circuit for 'relay lNC at contact finger 52 to` thereby'reniove brake applying device BA from under control ofthe relay NC. `Thus in order that relay NC be retained energized during travel through non-train control territory, it is necessary; that relay MR first release and subsequently pick up. Also, if for any reason the current ysupplied by the amplifier Werestrong enough to maintain the contacts .ofthe mainrelay MR attracted but not of a sufficient value to move these contacts from their full vcle-energized to their full energized position, the pick-up circuit for the non-control relay could not be completed for the reason that the contact finger 46 of the main relay vvould maintain'thisv pick-up circuit open. The operative condition of the main relay is thus checked atl every point Where Vthe train passes from equipped to unequipped'sections. v p

Referring now to Fig'. 2, a modied vform offapparatus for decreasing the sensitivity of the car-'carried receiving apparatus/has been shown. It should be'understood that the'amplifier shown in Fig. 2is designed to be usedin connection With suitable car-carlcuits is based on the fact that in a circuit including a transformer having very poor regulation, 'if an appreciable current is drawn, the voltage delivered by the transformer will be very greatly reduced.

The usual inductive receiving coils 18 and 19 vare provided and are connected as shown to the input circuit of a filter Which is identical with the filter shown in Fig. 1, its corresponding parts being referred to by the reference characters used in Fig. 1. The output circuit ofy the filter is tuned by the variable condenser 68, and is connected between the grid and ilamentof the first tube ofthe usual audio'n'tube amplifier. A potentiometer comprising the two variable resistances 69 and 70 is connected across the'filamentx'battery 34, inl such a manner that the bias or degree of potential on 'the grid circuit may be varied by connecting the grid return' from the filter to various points of the potentiometer. This change o-f'fconnection of the grid return is'a'cccniplished by a Inake-befoie-break contact finger '71 Vof the push button relay 26 having a back contact 72 connected to one extreme end of the kpotentiometer and afront contact 73' connected to its midpoint as clearly shown.

In operation, When the train is traveling over trackWay-equipped for train control operation, the pushbutton relay 26 is Anormally de-energized andA the voltages induced in the receiving coils 18and 19 are delivered vby the filter Yto the grid filament circuit of the-first tube 27'fof the amplifier inthe usual manner, this 'circuit being completed through ther contact finger 71 and the back contact 72 of the push button relay 26. The voltages are amplified and operate the train control apparatus inthe manner described in'connection With Fig. 1. Y When it isv desired to decrease the sensitivity of the receiving equipment in orderA to set up the `inactive* ornon-control condition described above, the'pushV button relay 26 is energized 'by depressing the push button 35 and the first engaging its front'contact 73 and then ried and traclwayv apparatus such as that disengaging its back Contact 72. '.Whe'n the front contact 7 3 is closed and the .back contact 72 is opened, the grid return circuit of the first tube 27 is connected to a point on the potentiometer which is more positive in polarity than the normalconnection through the back contact 72, and for this re'asona positive bias is placed onY the igridloffthis tube. Itis a Well known fact that if a` -positive bias isV placed onthe grid of an audion tube, its grid-filament circuit draws a current load instead of the pure voltage which actuates the grid circuit- `Whentlie grid-bias is negative. As the mavneticcoupling vbetween the track rails and the receiving coils is very poor, simula-ting in effect a transformer having a core with 'a'.large air'gap therein, the current drawn from thereceiving circuit When'the grid is biased positive VWill cause the voltage induced in thereceiving coils to drop by a large amount, consequently decreasing the voltage supplied to Y the amplifier, and` thereby greatly reducing the sensitivity of the entire receiving equipment. This scheme is, of course, vemployed in connection WithL an excess energy section on the trackway Aof the type vdescribed in connection with Fig. 1, and theexcess energy supplied causes the output current of the amplifier to be sufficient to energize the-main relay MR in spite of the reducedsensitivity duek to the positive' grid bias.

The degree to which the sensitivity of the Areceiving equipment` is reducedby the apa- `ratus shown in Fig. 2 maybe very accurately regulated by adjusting the values of the variable resistances 69 and 70 and: thereby adjusting the extent of the 'positive bias which isV placed upon the grid of the Afirst tube. By properly regulating Ythese valuesV of the resistances 69 and 70, a very large butdefinitely fixed reductions-in the sensitivity of the receiving equipment is produced, and proper control is maintained when non-control'fterritory is entered.

Referring now tov Fig.

in which no iiitcr circuit is used has been slioivn. In this mod-iication,.the amplifier has been represented conventionallyj at A, and the push button relay 26 with its push button 35 andits contact finger 74, control- :ling thel input circuit of the amplifier, has

been shown. In this schemepvhen the push button relay is cle-energized the tworeceivving coils 18 and 19 are connected in series to the input circuitv ofthe lamplifierin lthe usual manner through a. circuit Wliich may betraced as follows :v from the receivingcoil 18, Wires 75 and 76, the input circuit of the ampliiier'A, Wire 77,*conta'ct finger 74 and back contact of the push button relay"26, Wires 78 and79, receiving coil'19A and Wires r'8O-and 81 to the receiving coil 18. `lliecirc 3, a modified'. method of reducing the sensitivityof the Y car-carried receiving equipmenton a system 'l j trol territory, and the tap 96 being connectcuitV justk traced' is preferably tuned to resonance at thel train control frequency by means of the condenser82 which is connected in parallel with the tivo receiving kcoils 18 and 19 as clearly shown.

When it is desired to reduce the sensitivy' ity o fl the receiving equipmentl to render the car-carried equipment inactive as described above, the'I push buttonl relay 26 is energized by depressing the push button 35 and the 75 contact linger 74 engages its front contact.

An alternative input circuit for the amplifier A is now completed, which circuit includes Yonly one of the receiving coils and may be traced asfolloWs:-from the receiv-` ,80

n ing coil 18,ivires 75 and 76,Y the input circuit of the 'amplifier A, Wire 77, contact linger 74 and front contact of the push button relay 26 andlwires Sand 61v to the receiving coil- 18. It should be observed :thatip85 the circuit just traced through the receiving coil 18 aloneuis not tuned to resonance by tlie condenser82.- It is obvious that the voltagefsupplied to the inputV circuit yat the amplifier When the push button relay 26 `isir 90 energized'vvill' be approximately halfthe y 4voltage which is, supplied to this input circuit when this relayis cle-energized byirea- 'son of the fact that only one receiving `coilis connected to this receiving circuit, when the relay Y26 is in its energized condition. In additionto this, the circuit through the sinl 'gle receiving'coil 18 is not tuned to resonance and the voltage delivered theicbylis therefore inrealityflcss than one-lialfofithe volt-F age delivered bythe Ativo receivingcoils 18 and 19 connected in series.` f

l Referring nonT toFig. 4, another modified method of reducing the sensitivity of the lcar-carried apparatus has been shown. Itfii05 Ishould: be understood that this modification :is to beiused in connection with suitable carcarrie'd and traclrvvay apparatus suoli as-vhas beenV shown .in Fig; 1, the amplier` and ythe Winding of the transformer 22, the tapmo 95 being connected'to a point Von the trans- `formerrivinding which gives normal secondary voltage When operating in train cond ,t e uo a point on the `Winding Wherel the coupling is so low that nov appreciable secondary voltage results Aunless excesslenergy is suppliedrto the receiving coils 18 and 19.

The taps 95 and l96 are connected as shownG tothe back andfr'ont contacts respectively l1:0 amplifier as shown in Fig. 1.

The usual tuning condenser 23 is provided `across theV secondary circuit of` the transformer 22, and the Wires 97 and 98 are assumed yto be connectedtothe'grid and filament, respectively, of the firsttube of an In operation, When the push button is depressed and the relay 26 energized, the Contact finger 25 is raised to engage its front Contact, thereby connecting the receiving 1:15 circuit to the tap-96 of the transformer'22.

VIf at tl is point the vehicle is travelling over an excess energy section, vas'thefsection J of Fig. 1, the energy supplied to the receiving circuit *throughV the -coils 18 and 19 is :520 suflicient to energize the main relay MR 'through the amplifier and lto set up noncontrol conditions in the car-carried apparatus as described in connection Withthe operation of the system shown'in Fig. 1. If,

' A5 however, the relay 26'is energized VWhen the usual-train control current is flowing in the track rails under the train, the main relay MR is not energized because of the extremely loose vcoupling ofthe transformer 22 with i130 the vinput circuit connected to the tap 96,

a'ndnon-control conditions cannot ybe set up.

' From the foregoing description it Will be seen that amethod of rendering inactive the car-carried equipment of an automatic train 5 control system of the continuous inductive typehas' been provided. in4 Which the sensitivity of the receiving apparatus is substantially reduced by a fixed anddeiinite amount M in anovel and convenient nianner, and that- "4U-suitable equipment has beenl provided tooperate either under conditions 'of electrical Ypropulsion or Vwith the usual unelectrified trackway systems. v

Although the particular method ofrenderingy the car-carried equipment inactive and of reducing the sensitivity of the receiving equipment which comprises the present invention has been described in a rather specific manner and in connect-ion With a single specific train control system, it should be clearly understood that certain changes, additions and'modification's may be made Within the scope of the present invention. For instance, the system ofthe present invention is readily'applicable to the Well known three-position type ofv Vcontinuous inductive'train control, in Awhich case the method of reducing the sensitivity Would be applied to the receiving equipment associated With one set lof receiving coils only, and various other additions or combinations might be made WithoutY departing from the spirit of the invention as defined l bythe appended claims.y Y l Y -Whatit is desired to secure by Letters 1. In an automatic train controlsystem of the type in which influences corresponding to trafiic conditions are continuously -transmitted inductively from the trackway to a` moving vehicle, car-carriedl equipment for `controlling the vehicle brakes in accordance with said inductively received influences, and means for rendering said carcarried equipment inactive for vehicle travel over sections of trackway unequipped for train controll operation comprising, a section of trackway for` transmitting an excessive amount of energy to the vehicle, a re` Vceiving circuit on the vehicle including a step-up transformer, means for varying the operative relation 'of the transformer to the receiving circuit, and further car-carried means whereby said brake control apparatus may be rendered inactive if the sensitivity of said receiving circuit is reduced While lsaid excessive energy trackway section is being traversed.

2. In an automatic train control systemVA for a railway having a portion of its track- -Way equipped for automatic train control nient, a manually'actuable circuit controller for controlling the energization of said relay, means at the entrance to said unequipped, portion of trackway for delivering an excessive -amount of energy to said receiving equipment, and means for maintaining said brake control apparatus inactive, While traveling in the unequipped portion of trackway, said last mentioned means beingV actuated if said relay is energized While the vehicle is traversing said excessively energized trackivay means and being held actuated only if said relayV is returned to its normal u de-energized condition.

3. In an automatic train control system for a railway having a portion of its track- Way equipped for automatic train control and a. portion not so equipped, car-carried means for cont-'rolling the vehicle brakes in accordance With influences corresponding to trame conditions While the vehicle is `traveling in said equipped portion and for maintainingthe brake controlapparatus inactive When traveling in the unequipped portion of trackWay comprising, a main relay energized in accordance with control energy received from the track rails by inductive` receiving apparatus, a brake control device normally controlled by said main? r'elay, a manually Ael'iergizable relay acting When energized to reduce thev sensitivity of the inductive receiving.' apparatus, 'a secondary relayenergized through a back contact of said manually energizable relay and a front contacty of said main. relay and anoncontrol relay having .a pick-up circuit including a front .contactof said manually energizable relay,xa rontcontactof said main relay and back contact .of said .secondary relay, and a stick circuit including a backcontact ot said secondary relay and a front contact of the non-control relay, said non-control relayl acting` when" energized to maintain said brake control'device inactive.

el. In anautomatic train4 control system for a railway having aV portion of its track- Way equipped for automatic train control and a portion not so equipped, and rusing alternating current for propulsion purposes,

means for controlling the brakes of. the vehicle 1n. accordance with influencesl corresponding to traliic conditions comprising alternating currents of a frequency distinct.

from the propulsion current frequency flowing in the track rails, a car-carried receiving circuit including a transformer having a primary circuit and a secondary circuit, said circuits being tuned to resonance for the frequency of lsaid train control current, means controlled by said receiving circuit to control the vehicle brakes, and means for rendering said brake. control apparatus inactive for vehicle travel over said unequipped portions of trackway comprising, a section of trackvvay at the entrance to said unequipped portion supplied with an excessive amount ofcurrent of train control fre*- quency, a normally de-energized manually energizable relay on the vehicle acting when energized to change the connections of said transformer in the receiving f circuit to change the tuning thereof, and the energization of said normally cle-energized relay also rendering the means for controlling the vehicle brakes inactive il said relay is energized While the vehicle is traversing said excessively energizedV trackvvayv section.

5. In any automatic: train control system l'or a railway having a portion of its track- Way equipped for automatic train control and a portion not so equipped, a car-carried brake applying device and means for controlling said device in accordance with in'- `lluences corresponding to traiiic conditions inductively received from the trackway in said equipped portion comprising, a main relay and a receiving circuit, a non-control relay acting when energized to maintain said brake applying devicey inactive in said unequipped portions of trackvvay, and means whereby said non-control relay is energized only if said main relay is vfirst le-energized and then re-energized.

lin the receiving circuit normally controllingy -/6.. In an automatic train control system of the type inwhieh influences correspond- Ing te traino conditions are continuously transmitted inductivelyv from the trackway to a moving..vfehicle,.` car-carried `equipment for controlling the vehicle brakes in accord- Vance with vinductively Areceived influences, and means forkrendering said carcarried equipment inactive'for vehiclev travel. over` sections of trackway unequipped for traincontrol operation comprising, a seetionoftrackway for transmitting an excessive amount. oienergy to the vehicle, a receiving circuit yon the vehicle, a main relay the brake control, apparatus and a secondary relay controlled by the main krelay and in turn controlling. a circuit through the main relTay.f

7. In an automatic train control system `oi the type in which influences corresponding/ to trailic vconditions are continuously `transmitted inductively from the trackwayto a moving vehicle ear-carried equipment` forscontrolling theV vehicle brakes in accordiance -With' said inductively received influences, andV means for rendering said carcarri'ed equipment inactive for vehicle'travclover sections otrackWa-y unequi'pped Jfor train control `operation compr1sing,a sectionof trackway for transmitting` an e-Xcessive amount of energy tor the' vehicle, a receiving circuit on the vehicle, a. main relay in the receivingy circuit normally controllingthe brake. control apparatus, a secondary relay controlled by the main relay and in turn controlling ay circuit through the mainA relay, and. a non-control relay arranged to be. operated to assume control .of the brake control apparatus..

8.. In an automaticy train control system of the type in which influences corresponding to; traiic conditions arey continuously transmitted..inductively' from the trackway to a moving vehicle, vcar-carried equipment for controlling the vehicle brakesI in accordance :with said inductively received influences,v :and means for rendering said carcarried equipment inactive for vehiclel travel. over lsections of trackWay' unequipped for trai-n control operation comprising, a. section. of trackway forJ transmitting an excessive amount o-t'energytothe vehicle, a receiving circuit on the vehicle, a main relay -in the receiving circuit normallyy contro-liling the. brake control apparatus and: a secondary' relay controlled by the main relay and in turn controlling; a circuit through `the main relay, and a non-control relay controlled:jointlyy bythe main relay and the seconda-ry relay to cause the non-control relay toassume control of the bra-ke control apparatus.

9.1m an automatic train control system flor.. arailway having. a. portion 'of' its trackway equipped for` automatictrain control and a portion not so equipped, car-carried v'means foi` controlling the-vehicle brakes in accordance with influences corresponding to trailic conditions whilel the vehicle' is travel- Yingin said equipped portionand for maintaining the brake control` apparatus inactive when traveling in 'the unequipped portion of trackway comprising, a main relay energized in accordance with control energy received fromthe track'rails by inductive re-V ceiving apparatus, a brake control device normally Lcontrolled by saidvmain relay, a

manually energizable relay acting when energized to reduce the sensitivity of the inductive receiving apparatus, a secondary relay'controlled by said manually energized 4relay and a non-control relay acting when energized to maintain said brake control device inactive.

10. In an automatic train control systemv for a railway having a portion of. its track- Way equipped for automatic train control and a portion not so equipped,a car-carried brake applying device and means for controlling said device in accordancewithinfluences corresponding to traiiic Aconditions linvductively received from the trackway in said equipped 'portion comprising, amain relay and areceiving circuit, a non-control relay acting when energized to maintain said brakeV applying device inactive 1n said unequipped portions of trackway,y and a secondary relay controlling,^and controlled by, said main relay, whereby said non-control relay is energized if said main relay is lfirst cle-energized and then rer-energized.

11.v In an automatic train control system for a railway having a portion of its trackway equipped for automatic train-control and a portion not so equipped, car-carried brake `control apparatus continuously controlled in accordance with energy received -from the trackway through receiving equipment including a transformer, and means to change the connections of said transformer in said receiving equipment and thereby reduce the sensitivity of said receiving equipment. Y A

12. In an automatic train control system for a railwayk having a portion of its trackway equipped for automatic train control and a portion not so equipped, car-carriedV brake control apparatus continuously controlled-in accordancewith energy received from the trackway through receiving equipment including a transformer, and means to change the connections of said transfornier in said receiving equipment` and thereby reduce the sensitivity of said receiving equipment, means at theV entrance to said unequipped portion of trackway for delivering an excessive amount of energy to said receiving equipment, Vand means-for maintaining said brake control apparatus inactive, while traveling in the unequipped portion yof trackway, said last mentioned means being actuated if the transformer connections changing means is energized while the vehicle is traversing said exces.

sively energized tra'ckway means.

13. In an automatic train control system vfor a railway having a'portion of its trackkWay equipped for automatic train control and a portion not so equipped, car-carried brake control apparatus continuously controlled in accordance Vwith energy received from the trackway through receiving equipment including a transformer and an amplifying unit connected thereto, and means f for changing the taps of the transformer to which said unit is connected, whereby to vary the sensitivity of said receiving equipnient.

- 14. lIn an automatic train control system for arailway having a portion of its trackway equipped for automatic train control and a portion not so equipped, car-carried brake control apparatus continuously controlled in accordance with energy received from .the trackway through receiving equipment including a transformer and an aniplifying. unit connected thereto, and manuallyV actuable meansfor changing the taps of the transformer to which said unit is connected, whereby to vary the sensitivity of said receiving equipment.

l5. In an automatic train control systen; for a railway having a portion of its track -way equipped for automatic train control and a portion not so equipped, car-,carried means for controlling the vehicle brakes in accordance with influences corresponding to traflic conditions while the vehicle is traveling in said equipped portion and for maintaining the brake control apparatus inactive when traveling -in the unequipped portion .of trackway comprising, a main relay energized in accordance with control energy received .from the track rails by inductive receiving apparatus, aA brake control device normally controlled by said main relay, a,

manually energizable relay acting when energized to reduce the sensitivity of the inductive receiving apparatus, a secondary "insect-"mewhen traveling iny the unequipped portion of trackway comprising, a main relay energized in accordance with control energy received from the track rails byinductive recevingapparatus, a brakecontrol device normally controlled by said main relay a manually energizable relay actingwhen en.- ergized to reduce the sensitivity of the inductive receiving apparatus, a secondary relay controlled by, and in turn controlling, said main relay, said Vmanually yenergizable relay operable to simultaneously de-energize said main'and secondary relays, said main and secondary relays being timed on drop away characteristics to insure release of said main relay just before the release of said lsecondary relay, and-'a non-control relaycontrolled by both said main relay and secondary relay and acting when energized, to maintain said brake control' device inactive. Y

17. In an automatic train control system for a railway having ay portion of-itstrack.- way equipped yfor automatic' train control and a portion not so equipped, car-carried means for `controlling the vehicle brakes in accordance with influences corresponding to traffic conditions while the vehicle is traveling in said equipped portion and for maintaining the brake control apparatus inactive when traveling in the unequipped portion of trackway comprising, a main relay energized in accordance with control energy received from the track rails by inductive receiving apparatus, a brake control device normally controlled by said main relay, a manually energizable relay acting when energized to reduce the sensitivity of the inductive receiving apparatus, a secondary relay controlled by, and in turn controlling, said main relay, and a non-control relay controlled by both the said mainrelay and secondary relay and acting, whenenergized, to maintain said brake control device inactive, said non-control relay being slow to release whereby to prevent its release due to momentary interfering currents on the rails.

18. In an automatic train control system for a railway having a portion of its'trackway equipped for automatic train control and a portion not so equipped, car-carried means for controlling the vehicle brakes in accordance with influences corresponding to trafiic conditions while the vehicle is traveling in said equipped portion and for maintaining the brake control apparatus inactive when traveling in the unequipped portion of trackway comprising, a main relay energized in accordance with control energy received from the track railsby inductive receiving apparatus, a brake control device normally controlled by said main relay, a manually energizable relay acting when energized to reduce the sensitivity of the indu'ctive receiving apparatus, a secondary and secondary relays being timed on drop' away characteristics to insure release of said `main relay justbefore. the release of said secondary relay, and a non-control relay controlled by both said main relay and secondaiyre-lay and actingwhen energized, to

maintain said brake control device inactive, said' non-controlV relay being slow torelease whereby to: prevent its release due to momentary interfering currents on the rails.

19.- ln combination with an. electro-responsive device-and a source of alternating current, a reactor connected with said device, a condenser connected in parallel with the reactor to tune the reactor to resonance at the frequency of' said current, and a circuit for said source including a` portion ofi said reactor and tuned to resonance at the frequency of said current. A

20. In comin-nation,- a stretch of railway track,fmeans for at times supplying alternating current to the railsl of' said stretch, an auto transformer having la secondary tuned to resonance at the' frequency of such current, an electro-responsive device connected withsaid secondary, and a pick-up circuit receivingv energy from the track railsfand including the primary of said transformer and tuned to resonance at the frequency of said current.

21. In combination,V a stretch of railway y track, means for at times supplying alternating current to the rails of said stretch, an auto transformer having a secondary tuned to parallel resonance at' the frequency of said current, pick-up circuit for the primary of said auto transformer receiving energy from the rails and tuned tol series resonance at the frequencyof said current, Aand governing means controlled by energy delivered by' the secondary of said auto` transformer.

22. ln automatic train control system for a railway having a portion of its trackway equipped for automatic' trainV control and a portion# not sor equipped, means for automatically controlling the vehicle brakes in accordance with influences corresponding to t'raf'c conditions continuously received from the trackway in' said equippedportion including a receiving circuit and an kamplifier, and means for rendering said automatic brake, control means inactive for vehicle tra-vel in said unequipped portion of trackway including means for causing said amplifier to draw an appreciable current from said: receiving circuit and thereby reducing the sensitivity of said receiving: circuit. n .l

23. In an automatic train control system yfor a. railway having. a portion ofy its trackj Way equipped `for automatic` train control and a portion not so equipped, vehicle-carried lcontrol, apparatus for-'controlling Ythe vehicle brakes in accordance with iniiuences corresponding to tralic conditions received from the trackway in said' equipped portion,

Vreceiving equipment including an amplifier yand a receiving"circuithaving transformers of poor regulation therein, and means for maintaining the automatic vehiclel brake control apparatus inactive for vehicle travel Y over said unequipped portion Vof traclrway -carried automatic brake applying device,

means foi controlling said device when the vehicle is traveling over said equipped por- Y tion of'traclrway comprising, a receiving circuit including a transformer lhaving a poor regulation and connected tothe grid-filament circuit of an laudion tube ampliier,

means. for maintaining said automatic brake applying device inactiverfor vehicle travel over said unequipped.portion of traclrway comprising a section of trackway-.at the entrance to said unequipped portion having means for transmitting an `excessive amount of energy to said receiving circuit, anormally de-energized manually energizable car-carried relay acting when energized to cause the grid of .one tube of said audion tube ampliiier to assume a positive potential, thereby causing said amplifier to draw an appreciable current from said receiving circuit and reduce the power transmitted by said receiving circuit, andmeans for rendering and maintaining said bralre applying c device inactive if said car-carried relay is energized While the vehicle traverses said excessively energized section, and is deenergized wheiithe vehicle leaves said section.

25. In an automatic train control system for a railway having a portion `of its trackway equipped for automatic train control and a portion not so equipped, a vehicle-carried main relay, means comprising a receiving circuit including a .plurality of receiving coils for cont-rolling the energization of said main relay while the vehicle is traveling over said equipped portion of tracli'waygand apparatus for reducing the sensitivity. of said receiving circuit so that it will be capable of energizing said main relay only When supplied with an excessiveamonnt of energyv from the trackway,-said apparatus including a .circuit controller acting when actuated to reduce the number of receiving coils connected in said receiving circuit.

26. In an automatic train control system for a railway having a portion of its trackway equipped for automatic train control and a portion notV so equipped, a vehiclecarried automatic brake applying device, means for controlling said brake applying device in accordance With alternating control currents iiowing in the track rails in said equipped portion of trackway comprising a receiving circuit including a plurality of receiving coils tuned to resonance at the frequency of said alternating control curonly when anjeXcessive amount of energy is supplied from the trackway, and trackway meansk at the entrance to said unequipped portion of trackway for supplying an excessive amount of energy to said receiving circuit. i

f In testimony whereof I hereby afiix my WILLIAM D. HAILES.

signature.

als

Fico

"ist 

